Roundup: Cooler Master CryoFuze 7, CryoFuze 5 Violet, MasterGel Maker and Pro V2 Review – Thermal compound from gray to colorful

1 - Product presentation and technical data 2 - Test methods and equipment 3 - Measurement protocols and TIMA evaluation 4 - Thermal resistance 5 - Thermal conductivity, CPU and GPU simulation 6 - Microscopy and particle size 7 - Material analysis 8 - Summary and conclusion

Measurement according to ASTM D 5470-17

I generally measure the thermal pastes for my articles and the database according to ASTM D5470-17 and I also try to reduce most negative influences in advance. This is precisely why I work with an initial layer of 500 µm after the respective calibration, which I first heat slowly to 120 °C without much pressure, then cool down to 20 °C to finally heat it to the constant 60 °C of my measurements. Only then do I measure the thermal resistance or thermal conductivity under identical laboratory conditions at a constant 60 °C average paste temperature and from 400 µm downwards in steps of 25 µm. This is done in a standardized way, whereby all interfering factors (such as die distortions or non-coplanar contact surfaces) can be excluded. Controlled surface conditions, unidirectional heat flow conditions, parallel contact surfaces and precisely known clamping forces are guaranteed.

I use the TIMA5 from Nanotest, a compact all-in-one benchtop device that combines the measurement setup and the required PC in one device. It is a self-sufficient and, above all, automated measurement setup that I can also run in parallel to other tasks in the background. After all, who wants to sit and watch for 6 hours or more? A test series like this is virtually impossible to carry out manually. All data is saved directly to the NAS via the network. The device is recalibrated before each measurement (sensors for pressure and BLT).

As this all seems somewhat complex to outsiders, I have placed the individual assemblies against the function diagram so that you know where and how the measurements already explained take place. I have already explained in detail what happens in the background and how the whole thing works in the linked basic article. I don’t need to repeat all that again.

I will illustrate this once again in the already familiar diagram so that you can better visualize the meaning of these values to be determined. We can see that the effective thermal resistance affects both the material and the two contact surfaces. Yes, there are very sophisticated methods, including pulsed lasers, which can also evaluate the pure bulk value very accurately, but in practice we ALWAYS have contact surfaces. I use reference bodies with a standardized (low) roughness for the measurements so that I can also draw conclusions from these in practice. I then end up with two values, the effective thermal conductivity and a value averaged over all measuring points of the different layer thicknesses BLT minus the extrapolated contact resistance.

External cooling is provided by a laboratory chiller from IKA, which can maintain the water temperature almost to the nearest decimal place and which can not only cool but also reheat if necessary, so that the required 20 °C water temperature can always be maintained. The hoses were connected using Festo couplings and special hoses.

Test equipment for material tests, accuracy and test preparation

The material testing and measurement of the pastes and pads is carried out by my Keyence VHX 7000 with EA-300, which enables both exact measurements and fairly precise mass determinations of the chemical elements. But how does it actually work? The laser-induced breakdown spectroscopy (LIBS) I used for this article is a type of atomic emission spectroscopy in which a pulsed laser is directed at a sample in order to vaporize a small part of it and thus generate a plasma.

The emitted radiation from this plasma is then analyzed to determine the elemental composition of the sample. LIBS has many advantages over other analytical techniques. Since only a tiny amount of the sample is needed for analysis, the damage to the sample is minimal. This relatively new laser technique generally requires no special preparation of samples for material analysis. Even solids, liquids and gases can be analyzed directly.

LIBS can detect multiple elements simultaneously in a sample and can be used for a variety of samples, including biological, metallic, mineral and other materials. And you get true real-time analysis, which is a huge time saver. As LIBS generally requires no consumables or hazardous reagents, it is also a relatively safe technique that does not require a vacuum as with SEM EDX. As with any analytical technique, there are of course certain limitations and challenges with LIBS, but in many of my applications, especially where speed, versatility and minimally invasive sampling are an advantage, it offers distinct advantages.

I would first like to point out that the results of the percentages in the overviews and tables have been intentionally rounded to full percentages (wt%, i.e. weight percent), as it happens often enough that production variations can occur even within the presumably same material. Analyses in the parts-per-thousand range are nice, but today they are not useful when it comes to reliable evaluation and not trace elements. However, every day in the laboratory starts with the same procedure, because when I start, I work through a checklist that I have drawn up. This takes up to 30 minutes each time, although I have to wait for the laser to warm up and the room to reach the right temperature anyway.

• Mechanical calibration of the X/Y table and the camera alignment (e.g. for stitching)
• White balance of the camera for all lighting fixtures used
• Check alignment of LIBS optics and standard lens, calibrate alignment of laser to own optics (x300)
• Test standard samples of the materials to be measured and correct the curve if necessary (see image above)

I will leave the theory at that, because we are waiting for the measurements.